1 /*
2  * FIPS 186-2 PRF for libcrypto
3  * Copyright (c) 2004-2005, Jouni Malinen <j@w1.fi>
4  *
5  * This software may be distributed under the terms of the BSD license.
6  * See README for more details.
7  */
8 
9 #include "includes.h"
10 #include <openssl/sha.h>
11 
12 #include "common.h"
13 #include "crypto.h"
14 
15 
16 static void sha1_transform(u8 *state, const u8 data[64])
17 {
18 	SHA_CTX context;
19 	os_memset(&context, 0, sizeof(context));
20 	os_memcpy(&context.h0, state, 5 * 4);
21 	SHA1_Transform(&context, data);
22 	os_memcpy(state, &context.h0, 5 * 4);
23 }
24 
25 
26 int fips186_2_prf(const u8 *seed, size_t seed_len, u8 *x, size_t xlen)
27 {
28 	u8 xkey[64];
29 	u32 t[5], _t[5];
30 	int i, j, m, k;
31 	u8 *xpos = x;
32 	u32 carry;
33 
34 	if (seed_len < sizeof(xkey))
35 		os_memset(xkey + seed_len, 0, sizeof(xkey) - seed_len);
36 	else
37 		seed_len = sizeof(xkey);
38 
39 	/* FIPS 186-2 + change notice 1 */
40 
41 	os_memcpy(xkey, seed, seed_len);
42 	t[0] = 0x67452301;
43 	t[1] = 0xEFCDAB89;
44 	t[2] = 0x98BADCFE;
45 	t[3] = 0x10325476;
46 	t[4] = 0xC3D2E1F0;
47 
48 	m = xlen / 40;
49 	for (j = 0; j < m; j++) {
50 		/* XSEED_j = 0 */
51 		for (i = 0; i < 2; i++) {
52 			/* XVAL = (XKEY + XSEED_j) mod 2^b */
53 
54 			/* w_i = G(t, XVAL) */
55 			os_memcpy(_t, t, 20);
56 			sha1_transform((u8 *) _t, xkey);
57 			_t[0] = host_to_be32(_t[0]);
58 			_t[1] = host_to_be32(_t[1]);
59 			_t[2] = host_to_be32(_t[2]);
60 			_t[3] = host_to_be32(_t[3]);
61 			_t[4] = host_to_be32(_t[4]);
62 			os_memcpy(xpos, _t, 20);
63 
64 			/* XKEY = (1 + XKEY + w_i) mod 2^b */
65 			carry = 1;
66 			for (k = 19; k >= 0; k--) {
67 				carry += xkey[k] + xpos[k];
68 				xkey[k] = carry & 0xff;
69 				carry >>= 8;
70 			}
71 
72 			xpos += 20;
73 		}
74 		/* x_j = w_0|w_1 */
75 	}
76 
77 	return 0;
78 }
79